Extraction, structural characterization, and biological activities of a new glucan from Codonopsis pilosula

In this study, a powerful and rapid aqueous two-phase system (ATPS) method was used to extract polysaccharides from Codonopsis pilosula. The ATPS process was investigated with response surface methodology (RSM). At an ammonium sulfate concentration of 17%, ethanol concentration of 30%, and extraction temperature of 40 °C at pH 6, the total extraction yield of polysaccharides reached (31.57 ± 1.28)%. After separation and purification, a homogenized polysaccharide CPP 2-4 with molecular weight of 3.9 × 10⁴ kDa was obtained from the bottom phase. The physicochemical properties and structural features confirmed that CPP 2-4 was an α-1,6-glucan. Activity studies showed that the IC₅₀ of CPP 2-4 for DPPH radical scavenging was 0.105 mg/mL. The FRAP and ABTS assays showed that CPP 2-4 had strong antioxidant activity in a dose-dependent manner. Furthermore, CPP 2-4 inhibited NO release in RAW264.7 cells induced by lipopolysaccharide, which indicated a certain anti-inflammatory effect. This study improved the extraction rate of polysaccharides from C. pilosula and identified a glucan for the first time, that can contribute to a better understanding of the composition and structure of polysaccharides from C. pilosula and provide data support for the medicine and food homology of C. pilosula.